446 SYLLIDA. 
Habitat.—Under a stone in Blacksod Bay (Southern). 
Heligoland (Mecznikow). 
This is one of the interesting additions made by Southern on the south-western shores 
of Ireland. The structure generally is that of a Hesionid, but its special features consist 
in the peculiar lyre-shaped dorsal bristle (Plate CX XXIV, fig. 6), besides the bifid tips of 
the ventral series (figs. 6a and 6b), and the hood-like extension of the pygidium. Meczni- 
kow’s original description is diagnostic, and he mentions that he found a female with eggs 
in segments 13 to 24. 
CaASTALIA FUSCA, Johnston. 
Two varieties of this species were found by Southern on the west coast of Ireland. 
The first was dredged in Clew Bay in 24 fathoms, on a bottom of sand and shells, and differed 
from the ordinary form in having red eyes, the absence of spines on the terminal portions 
of the bristles, which are shorter and thicker ; the terminal pieces tend to be bifid at the tip, 
and the bevelled end of the shaft is bifid. In the second variety from Ballynakill Harbour 
the bristles are similar, but longer, the tips of the shafts pointed, not bifid, the terminal 
pieces are longer, with fine spikes, and the bifid nature of the tip is more distinct. The 
coarse spikes on the terminal pieces are absent. Further, in a number of segments in the 
middle of the body the dorsal division has a large curved spine (Southern). Horst? gives 
the extended distribution of this species and the synonymy. 
FAaMILy SYLLIDZA. 
In this family Caullery and Mesnil? propose to institute a new genus, viz., Parexogone, 
for the Padophylax hebes of Webster and Benedict, which Southern has procured on 
the west coast of Ireland, the head being formed into a sort of cone with fused palps. 
The anterior region of the alimentary canal is muscular, with proboscis, crop, and gizzard. 
The cuticle is thick. The animals frequent compact sand, and the habit for Syllids is thus 
peculiar. Moreover, an important paper on the group, with excellent illustrations, has 
recently been published by Prof. Haswell,’ in which both systematic and structural features 
as well as developmental investigations are detailed. Amongst other interesting structural 
points, he found that in some the nephridia of each pair unite completely at sexual maturity. 
In Exogone fustifera the extruded egg becomes attached by one end to the area on which 
the ducts of the pedal gland open—internal to the ventral cirrus. He points out that in 
Exogone fustifera the formation of the ccelom differs from that of the Polycheeta generally, 
since the stomodzeum ends behind in a mass of tissue (syncytium), im which the large yolk- 
granules are imbedded. ‘The changes in this take place before the young annelids become 
free. 
In a further paper Haswell* treats of the minute structure of the proboscis of the Sylhidee 
1 ‘Zoolog. Medeelingen, Deel vi, p. 76, 1921. 
* “Bull. Soc. Zool. France,’ xii, p. 127, 5 figs., 1918. 
> «Journ. Linn. Soe.,’ vol. xxxiv, p. 217, pls. xvi and xvii. 
* «Quart. Journ. Micr. Sci.,’ vol. 65, p. 328, pl. xv. 
